PROJECT SUMMARY Sleep duration and quality is worse among racial/ethnic minority groups, particularly African Americans/blacks and Hispanic/Latinos. Impaired sleep has been associated with detriments in cognitive function, which is a major cause of poor quality of life and disability among older adults. Impaired cognitive function is more often observed in racial/ethnic minority groups, including blacks and Hispanic/Latinos, leading to greater disparities in well-being among these groups. Given the importance of maintaining cognitive function at older ages, we propose to examine sleep disparities among a cohort of 480 older adults (65-85 years) from three racial/ethnic groups to understand better the correlates of these sleep disparities and to examine the role sleep plays in cognitive function disparities. Impaired cognitive function can lead to disabling forms of dementia, including Alzheimer?s disease. If inadequate sleep is a significant correlate of worse cognitive function among older adults, the development of novel therapies and behavioral interventions to improve sleep in older adults, particularly ones tailored to the specific needs of racial/ethnic minorities, could have a significant impact on public health and help to eliminate disparities. Defining the correlates of inadequate sleep and the contribution of sleep to cognitive function in a racial/ethnically diverse sample is the first step towards identifying modifiable factors within each racial/ethnic group contributing to sleep and cognitive function. Another goal is to further elucidate the mechanisms through which inadequate sleep is associated with impairments of cognitive function in order to identify additional therapeutic targets. Inadequate sleep has been associated with adverse cardiovascular function, including higher blood pressure and heart rate, greater carotid intima media thickness and elevated ratio of white matter hyperintensities to normal tissue in the parietal region of the brain. Inadequate sleep has also been associated with increased insulin resistance and diabetes risk in experimental and observational studies. Cerebral small vessel disease and insulin resistance are risk factors for the development of impaired cognitive function and Alzheimer?s disease. We will enroll 160 non-Hispanic blacks, 160 non-Hispanic whites and 160 Hispanic/Latinos without severe cognitive impairment. We will define the contribution of psychological and social well-being to sleep disparities in older adults and we will determine the contribution of inadequate sleep to disparities in cognitive function and health-related quality of life. Finally, we will explore whether cerebral small vessel disease and insulin resistance are potential mechanisms linking inadequate sleep to impaired cognitive function in older adults. This application aligns with the goals of the NIH Sleep Disorders Research Plan to ?Identify ? lifestyle factors ? contributing to the risk of sleep and circadian disorders and disturbances, and their role in the development and pathogenesis of co-morbid diseases, and disability.?